UPDATE: Explosions at Boston Marathon

WASHINGTON (AP) -- An intelligence bulletin issued to law enforcement includes a picture of a mangled pressure cooker and a torn black bag that the FBI says were part of a bomb that exploded during the Boston marathon.

The bulletin was obtained by The Associated Press.

The FBI says it has evidence that indicates one of the bombs that exploded in the Boston Marathon was contained in a pressure cooker with nails and ball bearings, and it was hidden in a backpack.

The FBI says the other explosive was in a metal container, but there wasn't enough evidence to indicate that it was a pressure cooker.

It was not known what was used to set off the two explosives that killed three people Monday and injured more than 170 others.

UPDATE, 4/16/13, 4:58 p.m.

WASHINGTON (AP) -- A Massachusetts congressman says investigators still don't know whether the Boston Marathon bombs were the work of domestic or foreign attackers.

Democratic Rep. William Keating says Homeland Security Secretary Janet Napolitano told him Tuesday that there was no intelligence chatter before the attack Monday that killed three people and wounded more than 170 others. No one has taken responsibility for the twin bomb blasts.

Earlier Tuesday Napolitano said there also was no evidence that the Boston attack was part of a broader plot.

UPDATE, 4/16/13, 10:00a.m

Massachusetts Gov. Deval Patrick says no unexploded bombs were found, only explosives were the ones that went off.

No additional threats are known.

UPDATE, 4/15/13, 8:02 p.m.A third person has died.

UPDATE, 4/15/13, 7:00 p.m.

BOSTON- Boy, 8, one of two killed in the Boston bombings, source says; 132 injured, 17 still in critical condition.

WASHINGTON (AP) -- President Barack Obama, responding to the explosions at the Boston Marathon, says the United States does not know "who did this or why" but vowed that whoever is responsible "will feel the full weight of justice."

He said: "We will find out who did this and we will hold them accountable."

Obama made his remarks Monday evening from the White House about three hours after two explosions detonated near the marathon's finish line. At least two people were killed and 50 injured in the blasts.

Obama has been in touch with federal law enforcement and Massachusetts officials in the aftermath of the explosions.

The Secret Service reacted cautiously to the blasts, expanding the security perimeter around the White House.

UPDATE, 4/15/13, 5:35p.m.

BOSTON (AP) -- Boston police say no suspect has been taken into custody in connection with the explosions near the finish line of the Boston Marathon.

Police Commissioner Edward Davis also says that the fire at a library a few miles away and more than an hour later doesn't appear to be related to the explosions at the race on Monday. He says the fire may have been caused by an incendiary device.

Authorities say the blasts killed two people and injured at least 73.

Police say it's too early to get into specifics about the nature of devices or whether shrapnel was involved.

UPDATE, 4/15/13, 4:29p.m.

WASHINGTON (AP) -- The Secret Service says it has expanded its security perimeter at the White House following the explosions at the Boston Marathon.

Secret Service spokesman Ed Donovan says the measure was taken "out of an abundance of caution." He says it is not unusual to expand or contract the security perimeters.

Shortly after the explosions Monday, Secret Service shut down Pennsylvania Avenue outside the White House, cordoning off the area with yellow police tape. Several Secret Service patrol cars also blocked off the entry points to the road.

The White House was not on lockdown and tourists and other onlookers were still able to be in the park across the street from the executive mansion.

UPDATE, 4/15/13, 4:02p.m.

BOSTON (AP) -- Boston police say there's been a third explosion in the city, following two blasts near the finish line of the Boston Marathon that killed two people and injured many others.

Police Commissioner Edward Davis says authorities aren't certain that the explosion at the JFK Library was related to the other blasts, but they're treating them as if they are.

UPDATE, 4/15/13, 3:45p.m.There were at least 3 runners from Bowling Green at the marathon, WBKO has spoken with one who said he finished the race minutes before the explosion happened, he is now safe in his hotel room.

For a list of all entrants click the link at the bottom of this story.

Two more explosives have also been found

Police in Los Angeles, New York City, London and other cities worldwide are stepping up security following explosions at the Boston Marathon.

Los Angeles County Sheriff's spokesman Steve Whitmore says the department has opened an emergency operations center, increased patrols for transit and other critical areas including the Los Angeles Dodgers game Monday night

Chief NYPD spokesman Paul Browne said Monday that critical response teams are deployed around the city. Officials are stepping up security at hotels and other prominent locations.

British police also say they are reviewing security plans for Sunday's London Marathon. It's the next major international marathon. A London Metropolitan Police spokesman says police are working with marathon officials to review security plans.

UPDATE, 4/15/13, 3:15

Two people confirmed dead, 22 are injured.

ORIGINAL STORY

BOSTON (AP) -- Spectators and runners are describing the twin explosions that shook the finish line of the Boston Marathon today.

One woman says she was waiting for her husband to cross the finish line, and, in her words, "it just blew." She described it as "a loud boom, and then glass everywhere." Cherie Falgoust says something hit her head, and she "just ducked."

A runner, Laura McLean of Toronto, says she heard two explosions outside the medical tent. She says, "There are people who are really, really bloody." McLean says, "they were pulling them into the medical tent."

The explosions took place about three hours after the winners crossed the finish line. The second one could be heard a few seconds after the first one.

A runner said, "There are a lot of people down."

Marathon workers were seen carrying one woman, who did not appear to be a runner, to the medical area as blood gushed from her leg.

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